Incidents of environmental pollution through oil spillage in both fresh and salt water are all too common. Recent history has evidenced the disastrous results that are caused by oil spills. Spilled oil causes damage to marine life, contamination of the water itself damage to the shoreline and damage to birds and other wild life that is dependent upon the contaminated water. Because oil spills cause great losses both environmentally and, of course, financially, processes for remediating the effects of oil spills are in great need.
Several methods of treating oil spills are known. Various mechanical devices such as fences, booms, and skimmers have been used to physically contain or remove oil that has been spilled on a water surface. In addition, several types of oil adsorbents have also been used in the past, such as, for example, straw. Various chemical treatments have also been used to either contain or coagulate spilled oil. For example, U.S. Pat. No. 3,755,189 teaches a composition for the control of oil floating on water that comprises a drying oil, a solvent and a catalyst used in combination as a composition that is able to confine oil that is floating on the surface of water. In addition, U.S. Pat. No. 3,977,967 teaches a method of containing oil spills that uses a polymer of high molecular weight that is able to gel or coagulate the spilled oil such that the coagulated oil can be raked off the surface of the water.
While these existing methods aid in removing spilled oil from the water surface, they fail to provide an adequate environmentally acceptable solution which is able to confine, coagulate and control spilled oil before the oil contaminates adjacent shorelines or drops below the surface of the water and forms an emulsion with the water. Due to the nature of oil and water, i.e. the lighter components of oil typically evaporate from the surface of the water in 24-28 hours, while the heavier components of the oil typically sink below the surface of the water and form an emulsion with the water. Emulsion formation is a particular problem in rough waters and, with current technology, removal of the oil from the contaminated water is virtually impossible once the oil has emulsified. There is therefore a continuing need for improved methods of remediating oil spills.
Another area of environmental concern is the proliferation of wastewater ponds to collect domestic, industrial and agricultural waste. For example, the last decade has witnessed a change in the production of livestock and dairy products from small, family owned units, to large corporate owned farms. As a direct result of this evolution, large wastewater ponds have been constructed to consolidate waste handling and remediation. However, the increased production of these large farms has also resulted in increased waste which directly impacts air and water quality in the surrounding area. Although a variety of methods of remediating the pollution caused by waste collection ponds have been proposed, many are expensive and few allow reuse of the aqueous collection medium after separation of the waste. Again, therefore there is a need for improved methods for mitigating the pollution caused by waste collection ponds.
A further common source of environmental pollution is the build up of nitrogen and other potentially harmful compounds in the soil and groundwater as a result of elution from fertilizers, herbicides and pesticides used in agriculture. In the case of nitrogen compounds, these frequently collect in lakes, ponds, rivers and estuaries increasing the levels of nutrients in the water and thereby allowing the rapid growth and maintenance of elevated population of suspended or filamentous algae. Not only are these algae growths unsightly but they also put stress on the aquatic and fish populations, frequently causing fish kills and the general decline of the quality of a water body. Although various methods have been proposed for denitrification of water and soil, these methods often involve the addition of agents that can themselves provide an additional source of environmental concern. There is therefore a need for improved methods for mitigating the pollution caused by fertilizers, herbicides and pesticides.
In U.S. Pat. No. 4,875,938 there is described a method of making a cementitious binder for use in mortars comprising heating marine shell material to about 2100 to 2350° F. (1150 to 1290° C.); allowing the shell material to cool to ambient temperature; mixing water with the cooled shell material in the ratio of about one part of water by volume to about five parts of shell material by volume; allowing said mixture to spontaneously heat; and monitoring the heat level of said mixture until it commences to cool and as it cools is converted into a dry, substantially white, powdery material that is substantially of the consistency of talcum powder and is useful as a binder in mortar.
Although the mechanism of the processes involved in the production of the cementitious binder described in U.S. Pat. No. 4,875,938 are not fully understood, it is believed that heating of the marine shell to high temperature converts calcium carbonate in the shell to calcium oxide and then the subsequent treatment with water converts the calcium oxide to calcium hydrate, Ca(OH)2, a highly exothermic reaction.
According to the present invention it has now been found that the powdery calcium hydrate product of the process described in U.S. Pat. No. 4,875,938 is effective in mitigating many types of pollution by binding the pollutant in an environmentally safe material. In the case of oil spills, it is found that if the calcium hydrate product is added to a body of water contaminated with oil, either as a surface layer or as an emulsion, the product binds with the oil, causing the oil to separate from the water and fall to the bottom of the body of water with the calcium hydrate product, leaving behind a clear and uncontaminated water layer. Since the calcium hydrate product is produced from shells or similar animal skeletal material, it poses no environmental hazard being left in the water until the oil is removed or is allowed to decay. The calcium hydrate product is similarly effective in binding and separating waste in a collection pond leaving behind a water layer that is sufficiently pure for reuse as a collection medium. In the case of fertilizers, herbicides and pesticides, the binding effect of the calcium hydrate product reduces the rate at which potential pollutants are eluted into the soil and groundwater.